Potential transformer having a bar-shaped magnetic core

ABSTRACT

A potential transformer having a bar-shaped magnetic core is provided. A winding assembly includes a primary winding which is wound on the core and a secondary winding which is wound on the primary winding. A cone-shaped coil supporting insulator is provided and is fixed at a flange portion thereof to a tank, which houses the components of the transformer. The core is supported at a center portion of the insulator, and the winding assembly is supported on the inside wall of the insulator. A magnetic shield is provided so as to cover the assembly and is attached to the inside wall of the tank. An insulation gas is filled in the tank.

[54] POTENTIAL TRANSFORMER HAVING A BAR-SHAPED MAGNETIC CORE [75] Inventors: Shinichi Menju; Hirokuni Aoyagi,

both of Kanagawa-ken, Japan [73] Assignee: Tokyo Shihaura Electric Company Ltd., Kanagawa-ken, Japan [22] Filed: Oct. 27, 1971 [21] Appl. No.: 192,921

[30] Foreign Application Priority Data 14 1 Jan. 2, 1973 2,062,014 11/1936 Piffath ..336/92 1,926,348 9/1933 Norviel et a1. ....336/92 X 1,499,931 7/1924 Jacobson ..336/92 2,416,148 2/1947 Borgend et al. 336/94 2,478,983 8/1949 Runbaken et a1. ..336/92 FOREIGN PATENTS OR APPLICATIONS 365,483 1932 Great Britain ..336/84 Primary Examiner-Thomas J. Kozma Attorney-Norman F. Oblon et al.

[5 7 ABSTRACT A potential transformer having a bar-shaped magnetic core is provided. A winding assembly includes a primary winding which is wound on the core and a secondary winding which is wound on the primary winding. A cone-shaped coil supporting insulator is provided and is fixed at a flange portion thereof to a tank, which houses the components of the transformer. The core is supported at a center portion of the insulator, and the winding assembly is supported on the inside wall of the insulator. A magnetic shield is provided so as to cover the assembly and is attached to the inside wall of the tank. An insulation gas is filled in the tank.

6 Claims, 4 Drawing Figures PATENTEUJAN 2 I975 3,708.7

SHEET 1 BF 2 INVENTORS smmcm MENJU 1 HIROKUNI AOYAGI BY g ATTORNEYS PATENTEWKJIT 2 m SHEET 2 [1F 2 2 G I F FIGH POTENTIAL TRANSFORMER HAVING A BAR- SHAPED MAGNETIC CORE BACKGROUND OF THE INVENTION 1. Field Of The Invention This invention relates to a potential transformer, and especially to a potential transformer having a barshaped magnetic core.

2. Description Of The Prior Art conventionally, a potential transformer comprises a tank, a magnetically closed core, and low voltage and high voltage windings. The low voltage winding is wound on the core through an insulator, and the high voltage winding is wound on the low voltage winding. The resultant combination is then positioned in the tank and the same is then filled with an insulating oil.

While somewhat satisfactory, the prior art transformer as described above is of a relatively large size, since a magnetically closed core is used and since the length between the tank and the high voltage winding must be great because of the necessity of providing insulation.

Moreover, since an insulation oil is used in the prior art transformer, the total weight thereof is very large, and should a fire develop, damage will spread rapidly.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a new and improved potential transformer having a bar-shaped magnetic core.

It is another object of the present invention to provide a new andimproved potential transformer having a bar-shaped magnetic core and which is of a relatively small size.

It is still another object of the present invention to provide a new and improved potential transformer having a bar-shaped magnetic core in which the elements of the transformer can be successfully sustained.

It is a further object of the present invention to provide a new and improved potential transformer having a bar-shaped magnetic core in which the leakage flux thereof is reduced.

One other object of the present invention is to provide a new and improved potential transformer having a bar-shaped magnetic core which will not be rapidly damaged in the presence of a fire.

Briefly, in accordance with the present invention, these and other objects are obtained by providing a tank for housing the components of a transformer. Means are provided for maintaining a bar-shaped core within the tank at the same potential as the primary high voltage. A winding assembly which includes a primary winding wound on the bar-shaped core and a secondary winding wound on the primary winding is provided. A cone-shaped coil supporting insulator is fixed at a flange portion thereof to the tank and the core is supported at the center portion of the insulator. The winding assembly is also supported on the inside wall of the insulator. A magnetic shield is provided to cover the winding assembly and for providing a return path for magnetic flux. The magnetic shield is attached to the inside of the tank and an insulation gas is filled within the tank.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a side view, partially in cross-section, of a potential transformer according to this invention;

FIG. 2 is a perspective view, partially cut away, of a potential transformer according to this invention;

FIG. 3 is a perspective view,partially cut away, of the coil supporting insulator shown in FIG. 1; and,

FIG. 4 is a plane view of the high voltage shield shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the Drawings, wherein like reference numerals designate identical, or corresponding parts throughout the several views, and more particularly to FIGS. 1 and 2 thereof, wherein the potential transformer of the present invention is shown as including a cylindrical tank 10 having an upper portion 1 and a closed bottom portion 3. A cone-shaped coil supporting insulator 9,which is preferably made of a polyethylene resin, has a flanged portion 7 which is positioned between and connected by bolts (not shown) to flanges 5 and 11 of the upper andlower portions 1 and 3 of the tank 10.

The coil supporting insulator 9 is shown in detail with reference to FIG. 3. In FIG. 3,it is seen that the insulator 9 is opened at a top portion thereof and a high voltage shield ring 15 is embedded and inwardly positioned at the mouth portion of the insulator 9. A round end shield 17 is partially inserted into the mouth portion of the insulator 9 so that the upper portion thereof extends through the shield ring 15. The round end shield 17 is fixed to the shield ring 15 by a nut 19 which is applied to the upper portion of the end shield 17.

Additionally, a bar-shaped core 23 is provided and has a hole penetrating therethrough for receiving a supporting bar 21. The bar-shaped core 23 is positioned on the end shield 17 through an insulating ring 25. An insulating cylinder 27 is then fitted around the barshaped core 23,and a shield winding 29 is wound around the cylinder 27.

A high voltage primary winding 31 is provided and is divided into a plurality of sections. Each section of the primary winding 31 is stacked over the shield winding 29, and is supported on an inside wall of the coil supporting insulator 9 by supporting members 33.

A secondary winding 37 is wound on the primary winding 31 through an insulator 35 to thereby form a winding assembly.

A flange 39 is provided at a top portion of the upper tank 1, and a cone-shaped insulator 41 is attached to the flange 39 by bolts (not shown). The cone-shaped insulator 41 is of a configuration similar to that of the coil supporting insulator 9. A shield ring 45 is embedded at a mouth portion of the insulator 41 and a rod contact 47 is attached to the shield ring 45. The uppermost or head portion of the contact 47 protrudes from the cone-shaped insulator 41 and is connected to the high voltage input.

A cup-shaped connecting conductor 49 is attached at a bottom portion thereof to the supporting bar 21. Finger contacts 51 are disposed between the connecting conductor 49 and the contact 47 such that the high voltage input supplied to the contact 47 will be led to the supporting bar 21 and then to the core 23. Now,since the potential of the core 23 is the same as that of the primary winding 31, the insulation between the core 23 and the primary winding 31 can be very easily made. Moreover, any potential unbalance resulting from the concave and convex shape of the surface of the core 23 is easily smoothed by the provision of the shield winding 29.

In addition, a high voltage shield cylinder 53 having four clamps 55 as shown in FIG. 4 is provided and serves to cover and insulate the high potential portions, such as the conductor 49. The shield cylinder 53 is attached to the supporting bar 21 by a cylindrically shaped clamp member 57. The clamp member 57 has a flange for connecting the clamps 55 of the shield cylinder 53.

Referring again to FIGS. 1 and 2, it is seen that fins 59 are provided over the tank for cooling the transformer therein. An insulation gas,such as sulpher-hexafluoride (SF )gas, is supplied to the tank 10 through an inlet 61 for insulating the elements therein. The insulation gas is exhausted through an outlet 63. A ground terminal box 65 for the primary high voltage and a secondary terminal box 67 are also provided at the tank 10.

It should further be understood that in accordance with the present invention, a plurality of magnetic shield boards 69, each having an elongated rectangular shape,are circumferentially separated and provided along the inside of the tank 10 to thereby provide a return path for the magnetic flux flowing within the tank and to prevent the generation of eddy currents. The boards 69 are secured to the tank 10 by bolts 71 and nuts 73.

It should further be understood that generally the tank 10 is positioned to stand vertically so that each element of the transformer is successfully sustained by the coil supporting insulator 9. However, if it is desirable not to have the tank positioned vertically,it is apparent that another coil supporting insulator may be provided and positioned to face with the coil supporting insulator 9 so as to support the winding assembly and other elements.

Thus, it should now be apparent that in the above embodiment, since a cone-shaped coil supporting insulator is provided,the winding assembly and other elements of the transformer are easily sustained. Furthermore,since the bar-shaped core 23 is at the same potential as the primary high voltage, a simple insulation is all that is needed between the core 23 and the primary winding 31. In addition, since the secondary low voltage winding 35 is positioned at an outer portion of the winding assembly, very little space is needed between the secondary winding 35 and the tank 10. As a result thereof,the size of the transformer is greatly reduced and a compact unit is realized. Additionally, it should be apparent that since magnetic shield boards 69 are provided that any leakage flux is greatly reduced.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A potential transformer having a bar-shaped magnetic core comprising:

a tank for housing components of said transformer,

a winding assembly including a primary winding wound on said core for receiving a high voltage and a secondary winding wound on said primary winding,

a cone-shaped coil supporting insulator having a flanged portion fixed to said tank, said insulator having a conically shaped inner surface for supporting said core at a center portion thereof and for supporting said winding assembly thereon,

magnetic shield means covering said winding assembly and attached to the inside of said tank, and

means for maintaining said bar-shaped core at the same potential as the high voltage applied to said primary winding, wherein said tank has an upper portion and a lower portion, each having flanges thereon and wherein said cone-shaped coil supporting insulator has a flanged portion which is positioned between the flanges of said upper and lower portions of said tank.

2. A potential transformer having a bar-shaped core according to claim 1 wherein,

said magnetic shield means are made up of a plurality of elongated rectangular magnetic boards which are separated from each other and which are positioned on the inner surface of said tank.

3. A potential transformer having a bar'shaped magnetic core according to claim 1, wherein said means for maintaining said bar-shaped core at the same potential as the high voltage applied to said primary winding includes:

a rod contact for receiving the high voltage input, 1

a cup-shaped connecting conductor, and

finger contacts connecting said connecting conductor to said rod contact.

4. A potential transformer having a bar-shaped core comprising:

a tank for housing components of said transformer,

said tank having an upper portion and a lower portion, each of which have flanges thereon,

a cone-shaped coil supporting insulator having a flanged portion which is positioned and mechanically connected between the flanges of the upper portion and the lower portion of said tank,

a shield ring provided at a mouth portion of said insulator and being partially embedded therein,

a round end shield which is attached to said shield ring,

a supporting bar which is attached to said end shield,

a winding assembly including a primary winding wound on said core for receiving a high voltage and a secondary winding wound on said primary winding,

means to support said winding assembly by said cone-shaped insulator,

magnetic shield means covering said winding assembly and attached to the inside of said tank,

tom portion thereof connected to said supporting bar, and

finger contacts connecting said connecting conductor to said rod contact whereby said high voltage input supplied to said rod contact will be led to said supporting bar and then to said bar-shaped core.

6. A potential transformer having a bar-shaped core according to claim 1, further comprising:

means for filling said tank with an insulating gas. 

1. A potential transformer having a bar-shaped magnetic core comprising: a tank for housing components of said transformer, a winding assembly including a primary winding wound on said core for receiving a high voltage and a secondary winding wound on said primary winding, a cone-shaped coil supporting insulator having a flanged portion fixed to said tank, said insulator having a conically shaped inner surface for supporting said core at a center portion thereof and for supporting said winding assembly thereon, magnetic shield means covering said winding assembly and attached to the inside of said tank, and means for maintaining said bar-shaped core at the same potential as the high voltage applied to said primary winding, wherein said tank has an upper portion and a lower portion, each having flanges theReon and wherein said cone-shaped coil supporting insulator has a flanged portion which is positioned between the flanges of said upper and lower portions of said tank.
 2. A potential transformer having a bar-shaped core according to claim 1 wherein, said magnetic shield means are made up of a plurality of elongated rectangular magnetic boards which are separated from each other and which are positioned on the inner surface of said tank.
 3. A potential transformer having a bar-shaped magnetic core according to claim 1, wherein said means for maintaining said bar-shaped core at the same potential as the high voltage applied to said primary winding includes: a rod contact for receiving the high voltage input, a cup-shaped connecting conductor, and finger contacts connecting said connecting conductor to said rod contact.
 4. A potential transformer having a bar-shaped core comprising: a tank for housing components of said transformer, said tank having an upper portion and a lower portion, each of which have flanges thereon, a cone-shaped coil supporting insulator having a flanged portion which is positioned and mechanically connected between the flanges of the upper portion and the lower portion of said tank, a shield ring provided at a mouth portion of said insulator and being partially embedded therein, a round end shield which is attached to said shield ring, a supporting bar which is attached to said end shield, a winding assembly including a primary winding wound on said core for receiving a high voltage and a secondary winding wound on said primary winding, means to support said winding assembly by said cone-shaped insulator, magnetic shield means covering said winding assembly and attached to the inside of said tank, an insulation gas filled in said tank, and wherein said bar-shaped core is shaped for receiving said supporting bar and is held at the same potential as the high voltage applied to said primary winding.
 5. A potential transformer having a bar-shaped core according to claim 4, wherein said means for maintaining said bar-shaped core at the same potential as the high voltage applied to said primary winding includes: a rod contact for receiving the high voltage input, a cup-shaped connecting conductor which has a bottom portion thereof connected to said supporting bar, and finger contacts connecting said connecting conductor to said rod contact whereby said high voltage input supplied to said rod contact will be led to said supporting bar and then to said bar-shaped core.
 6. A potential transformer having a bar-shaped core according to claim 1, further comprising: means for filling said tank with an insulating gas. 